Fatto generale: 21879 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 21879 is an uninteresting number.
Trivia: 21879 is an uninteresting number.
Data storica: November 25th is the day in 2008 that Cyclone Nisha strikes northern Sri Lanka, killing 15 people and displacing 90,000 others while dealing the region the highest rainfall in 9 decades.